/**
 * 844. 比较含退格的字符串
 * https://leetcode.cn/problems/backspace-string-compare/description/
 */
class Solution {
    public boolean backspaceCompare(String s, String t) {
        return changeStr(s).equals(changeStr(t));
    }

    public String changeStr(String s) {
        StringBuffer ret = new StringBuffer();
        for(int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i);
            if(ch != '#') {
                ret.append(ch);
            } else {
                if(ret.length() > 0) ret.deleteCharAt(ret.length() - 1);
            }
        }
        return ret.toString();
    }
}